a Other includes "flyaway
aircraft" or aircraft moving under their own power (i.e., aircraft
moving from the manufacturer to a customer and not carrying any freight),
powerhouse (electricity), vessels moving under their own power, pedestrians
carrying freight, and unknown and miscellaneous.

b Beginning in January 1996,
new edit checks were added to the processing of the Transborder Surface
Freight Data. Because of these checks,
the number of mail export shipments from the United States to Mexico declined
sharply between 1995 and 1996. The
Census Bureau found that a number of rail shipments were misidentified as
mail shipments in 1994 and 1995, although the exact proportion of these is
unknown.

c Foreign Trade Zones (FTZs)
were added as a mode of transport for land import shipments beginning in
April 1995. Although FTZs are being
treated as a mode of transportation in the Transborder Surface Freight Data,
the actual mode for a specific shipment into or out of an FTZ is unknown
because U.S. Customs does not collect this information.

NOTES

Shipments that neither originate nor terminate in the United
States (i.e., in transit, in-bond shipments) are not included here, although
they use the U.S. transportation system. These shipments are usually part of
Mexico-Canada trade, and simply pass through the United States. Transshipments, however, are included
between 1994, 1995, and 1996; these are shipments that entered or exited the
United States by way of a Customs port on the northern or southern border, but
whose origin or destination was a country other than Canada or Mexico. Starting in 1997, transshipments are
excluded. Users should note these
differences before comparing figures for 1994-96 with 1997 and subsequent
year data. Data exclude export
shipments valued at less than $2,500 and import shipments valued at less than
$1,250.

Numbers may not add to totals due to rounding.

SOURCE

U.S. Department of Transportation, Bureau of Transportation
Statistics, Transborder Surface Freight Data, Internet site
www.bts.gov/transborder as of July 27, 2004.